Tritium Production in a Sphere of ⁶LiD Irradiated by 14-MeV Neutrons

The specific production of tritium in a 600-mm-diam sphere of ⁶LiD irradiated by a central source of 14-MeV neutrons has been determined by measuring the tritium radioactivity in samples of ⁶LiH and ⁷LiH embedded in the sphere. Results are reported for several samples of each isotope at each of five different radii in the assembly. The entire process of decomposing the LiH samples, transferring the evolved gas into counters, and determining the decay rate was standardized by processing LiH samples irradiated by thermal neutrons, for which the ⁶Li(n,α) cross section is well known. These experiments provide benchmark measurements for checking calculations of neutron transport and tritium production in ⁶LiD. Tritium production in each ampule, as calculated using a three-dimensional Monte Carlo code, is in reasonable agreement with the experiment. For ⁷Li, discrepancies between calculation and experiment seem to be due to errors in the tritium production cross sections.